This invention has the purpose of facilitating a means by which pets can self activate automatic devices and allow humans to operate the devices remotely. The scope of this invention includes a modulated ultrasonic transceiver utilizing a fixed duration edge detect means to extend the range of the device by distinguishing between a low level transmitted signal and environmental noise. This is employed to control a wireless pet containment system; a sonic alarm for area restriction; a remote pet trainer and a remotely operated, fully automatic pet door but, its uses can easily be extended to other output devices.